The present invention relates to a plasma reactor electrode, and more particularly to a plasma reactor electrode which provides uniform cooling and consistent delivery of RF power.
Various structures of plasma reactor electrodes are known in the art. Two such structures are shown in U.S. Pat. Nos. 5,074,456 and 6,073,577. In U.S. Pat. No. 5,074,456, a silicon electrode is bonded to a support ring via brazing techniques, or through the use of a metal-filled epoxy. In U.S. Pat. No. 6,073,577, the electrode is bonded to a graphite support ring by an elastomeric joint. In both of these techniques, the silicon electrode is bonded only at one of its edges, and thus is bonded only along a limited contact surface. Such bonding creates a problem with respect to uniformity of heat transfer when RF power is delivered to the electrode.
It would be desirable to provide a plasma reactor electrode which provides more uniform transfer of heat, and which in addition transfers RF power so as to reduce voltage gradients in a showerhead assembly in which the electrode can be used.
In view of the foregoing, it is one feature of the invention to provide a plasma reactor electrode structure which avoids the above-identified deficiencies, and provides the foregoing and other advantages.
In accordance with one embodiment of the invention, an upper plate and a lower plate are connected with pins or studs, heat being transmitted from the lower plate to the upper plate at least in part via these pins or studs. This structure also provides more efficient delivery of RF power, to reduce voltage gradients in a showerhead assembly in which the electrode may be used. By reducing the voltage gradients, there is less tendency for an arc to form, or a spurious discharge.
Another feature of the invention relates to a method for fabricating such a plasma reactor electrode.